MarinePure GEMS 90g
Pack size
90 g
Suits tanks
Up to 284 L
Water type
Freshwater + Marine
Media type
Ceramic biomedia
MarinePure GEMS 90g
The GEMS box CerMedia actually rates a bioload figure for. MarinePure GEMS 90 g are small ceramic pellets made by CerMedia (USA) from the same aluminosilicate ceramic as the full-size MarinePure Spheres and Plates, fired above 1,000°C to create a rigid, open-pore structure. Each pellet is about 19 mm (¾") across. Unlike the 50 g Fresh GEMS pack, this 90 g box is rated by CerMedia for both freshwater and marine nano and small tanks, and comes with a published bioload figure to size a filter against.
Key features
- Manufacturer-rated bioload – CerMedia states this box supports tanks up to roughly 70 US gallons (265 L), the only GEMS pack size with a published figure.
- Over 135 m² (1,450 sq ft) of surface area – packed into a 90 g box, using the same ultra-porous ceramic as the full-size Spheres.
- Fresh and marine safe – unlike the 50 g Fresh GEMS pack, this size is rated for reef and marine nano tanks as well as freshwater.
- Resists clogging – the ceramic structure holds its shape, so flow through the media stays consistent between cleans.
- Reusable – rinse in tank water at a water change rather than replacing on a schedule.
Specifications
| Brand | MarinePure (CerMedia, USA) |
|---|---|
| Pack size | 90 g (3.2 oz) |
| Pellet size | Approx. 19 mm (¾") diameter |
| Material | Inert aluminosilicate ceramic, fired above 1,000°C |
| Open porosity | 80–90% |
| Total surface area | Over 135 m² (1,450 sq ft) per box |
| Rated bioload | Up to 70 US gallons (265 L) |
| Water type | Freshwater and marine |
| Filter compatibility | Canister, hang-on-back and internal filters with a media basket |
Which GEMS box do I need?
| Pack | Surface area | CerMedia bioload guidance | Best suited to |
|---|---|---|---|
| Fresh GEMS 50 g | Approx. 65–85 m² (700–915 sq ft) | Not published by CerMedia for this pack size | Freshwater community, planted and tropical tanks in small canisters or hang-on-back filters |
| GEMS 90 g | Over 135 m² (1,450 sq ft) | Up to 70 US gallons (265 L) | Freshwater and marine nano and small tanks |
If you're stocking a marine nano or reef tank, or you simply want a bioload figure printed on the box rather than working it out yourself, the 90 g pack is the one CerMedia backs with a number.
Suitable for, and not suitable for
- Suitable for: freshwater and marine nano and small tanks up to around 70 US gallons (265 L), run through a canister, hang-on-back or internal filter with a media basket that takes loose pellets.
- Not suitable for: larger systems as the sole biological media – past roughly 70 gallons, MarinePure Spheres, PODs or a Plate carry more surface area per dollar and per litre of basket space. Not a mechanical or chemical media – it won't polish water or remove odours on its own.
Care and maintenance
Rinse GEMS in tank water or dechlorinated water at a water change – never under tap water straight from the mains, since chlorine and chloramine will knock back the bacterial colony. There's no fixed replacement interval; the ceramic doesn't wear out, so GEMS keep working until the filter basket is due for a clean.
Goes well with
- MarinePure Mesh Bag (Small) – keeps loose GEMS contained and easy to lift out for a rinse.
- A marine or reef salt mix – if this box is going into a new marine nano setup rather than an existing tank.
- An ammonia and nitrite test kit – confirm the media is cycled before stocking up.
Warranty and delivery
MarinePure GEMS 90 g has no stated wear-out life from CerMedia – it's ceramic, not a consumable cartridge – and any manufacturing fault is covered by your rights under Australian Consumer Law in addition to any retailer or manufacturer terms. Standard parcel freight applies.
Common questions
What's the difference between the 50 g and 90 g GEMS boxes?
Both use the same ceramic pellets. The 90 g box has more surface area, carries a published bioload rating of up to 70 US gallons (265 L), and is the one CerMedia rates for marine and reef tanks as well as freshwater. The 50 g Fresh GEMS box is freshwater-only and doesn't come with a stated bioload figure.
Can I run GEMS in a reef tank?
Yes – this 90 g pack is fresh and marine safe and suits nano reef setups where a full MarinePure Sphere box would be more media than the sump or filter can hold.
Do I need to cycle a filter before adding livestock?
Yes. GEMS need time for bacteria to colonise the ceramic before they're doing useful biological work. Run the filter on established tank water, or fishless-cycle with an ammonia source, before stocking up.
How long does a box of GEMS last?
Indefinitely, with a periodic rinse. Ceramic biomedia isn't a wear item like filter floss – replace it only if it's physically damaged.
